JP4206874B2 - Planar light emitting device - Google Patents

Description

  The present invention relates to a planar light emitting device used for a liquid crystal backlight, a panel meter, an indicator lamp, a surface emitting switch, and the like.

2. Description of the Related Art Conventionally, a planar light emitting device that emits light from a semiconductor light emitting element, for example, a light emitting diode (hereinafter referred to as LED) in a planar shape, is used as a light source such as a liquid crystal backlight. An example of the structure of the planar light emitting device is shown in FIG. The planar light emitting device 100 includes a translucent light guide plate 101 and an LED 102 that is provided on one end surface of the light guide plate 101 and allows light to enter from the end surface of the light guide plate. Light from the LED 102 is reflected by the reflector 103 and guided to the incident surface 105 of the light guide plate 101. Further, a reflection plate 104 is provided except for the exit surface 106 of the light guide plate 101 and the end surface where the LEDs are opposed to each other, and incident light from the LED 102 is reflected by the reflection plate 104 and exits from the exit surface 106. Also, a prism sheet (not shown) separate from the light guide plate is arranged on the emission surface in order to improve the luminance of the backlight by increasing the ratio of the light emitted in the emission surface direction (for example, Patent Literature 1) has also been proposed.
JP 2002-107515 A (paragraph number [0014], FIG. 1).

  However, in order to further increase the luminance of the LED, which is a light source, in order to increase the light emitting area of the planar light emitting device or to emit light with higher luminance, there are the following problems. That is, the light from the LED has a directivity characteristic of emitting light radially with a certain directivity angle. For this reason, the light emission intensity in the vicinity of the LED is strong, and the light emission intensity is weakened as the distance from the LED is increased, so that uneven brightness tends to occur. In particular, the corners seen between the LEDs and from the exit surface side tend to be dark. Furthermore, when a high-brightness LED whose emission intensity has been improved to several thousand mcd is fully emitted, there is an advantage that the number of LED chips can be reduced and the size can be reduced. An intensity distribution occurs. On the other hand, a method can be considered in which a reflection pattern is provided on the bottom surface facing the exit surface of the light guide plate, and incident light is scattered and reflected within the light guide plate to make the luminance uniform. However, with this method alone, it is difficult to eliminate the intensity distribution of light emission in the vicinity of the LED.

In addition, when the prism sheet is used, it is difficult to reduce the thickness of the light emitting device, and the manufacturing process becomes complicated due to an increase in the number of components.
Accordingly, an object of the present invention is to provide a planar light emitting device having high luminance and uniform luminance.

  In order to solve the above problems, a planar light-emitting device of the present invention is a light-emitting device that includes a light source and a light guide plate that causes light from the light source to be incident from the side surface and to be emitted from the upper surface by reflection. An uneven portion is provided on at least one of the side surfaces. Here, the concavo-convex portion includes a side surface facing a side surface on which light from the light source is incident, a side surface adjacent to a side surface on which light from the light source is incident, a side surface on which light from the light source is incident, and the light guide plate Each can be provided on the top surface.

  The planar light emitting device of the present invention has an uneven portion on at least one side surface of the light guide plate, and light from the light source is reflected by the uneven portion on the side surface. Thereby, the transmission of light from the side surface is suppressed, and the light extraction efficiency can be improved without using a prism sheet.

  Moreover, the planar light-emitting device of this invention can use the prism row | line | column which consists of many protrusions which have a continuous triangular cross section as an uneven | corrugated | grooved part.

  Moreover, the planar light-emitting device of this invention is arrange | positioned so that a light source may oppose the entrance plane of the said light-guide plate, and an uneven | corrugated | grooved part can also be provided in an entrance plane.

  Moreover, the planar light-emitting device of this invention can also make it arrange | position with a pair of side surface which a light-guide plate opposes as an incident surface, and opposes a light source to each of the pair of incident surface.

  In the planar light emitting device of the present invention, since the uneven portion is provided on at least one side surface of the light guide plate, the light from the light source is reflected on the uneven portion, and transmission of light to the side surface can be prevented. Thereby, the light extraction efficiency can be improved without using a reflector. Furthermore, by providing an uneven portion on the emission surface, the emission direction can be adjusted and the proportion of light emitted perpendicular to the emission surface can be increased, so that the emission luminance can be increased.

  Embodiments of the present invention will be described below with reference to the drawings. However, the embodiment described below exemplifies a planar light emitting device for embodying the technical idea of the present invention, and the present invention does not limit the planar light emitting device to the following. Further, the size and positional relationship of the members shown in the drawings are exaggerated for clarity of explanation.

Embodiment 1 FIG.
1A and 1B are schematic views showing the structure of a planar light emitting device A according to the present embodiment, where FIG. 1A is a plan view and FIG. 1B is a perspective view. The planar light-emitting device A includes a light-transmitting light guide plate 3 and a light source array 1 including a plurality of light sources 1a that are linearly arranged on one side surface of the light guide plate and allow light to enter from the side surface of the light guide plate. Has been. Here, the light guide plate 3 is the upper surface of the light guide plate 3 and emits light that has been transmitted through the light guide plate. The light exit surface 3a, the bottom surface 3b facing the light exit surface 3a, and the side surface receive light from the light source. Incident surface 3c, side surface 3d facing the incident surface 3c, and a pair of side surfaces 3e and 3f adjacent to and facing the incident surface 3c.

  In the present embodiment, the surface of the light guide plate 3, that is, any one or more surfaces selected from the exit surface 3a, the bottom surface 3b, the entrance surface 3c, the side surface 3d, and the side surfaces 3e and 3f is shown in FIG. The concavo-convex portion formed of the prism row shown in (b) can be formed. For example, in the case where the concavo-convex portion including the prism row shown in FIG. 1B is formed on the entire surface of the light guide plate 3 excluding the light source mounting surface 3g, one of the light from the light source incident on the light guide plate 3 from the incident surface 3c. The portion is reflected in the inner direction of the light guide plate 3 by the side surface 3d facing the incident surface 3c, the side surfaces 3e and 3f adjacent to the incident surface, and the bottom surface 3b, and the light reflected to the incident surface side is other than the mounting surface It is reflected by the incident surface and returns to the inside of the light guide plate. The reflected light is refracted by the prism array provided on the emission surface 3a, or is reflected and then refracted and emitted to the emission observation surface side.

  According to the present embodiment, it is possible to prevent the transmission of light on the side surface without using a reflector, and thus it is possible to improve the light extraction efficiency. Further, the prism row provided on the exit surface acts to adjust the exit direction so that the proportion of light exiting perpendicular to the exit surface increases. Accordingly, the luminance of the light emitting device can be improved. In addition, when a high-brightness LED is fully lit as a light source, an extremely strong emission intensity distribution is generated in the vicinity of the LED, but by providing a prism row on the incident surface, transmission of light from the incident surface is prevented. And since light can be introduce | transduced into the dark part near LED, a brightness | luminance can also be equalize | homogenized.

  In addition, conventionally, the reflective plate has been used a sheet-like material molded by adding a white pigment or a scattering material to a resin such as polyethylene terephthalate, polycarbonate, and polypropylene, but according to the present embodiment, Since the reflector is not necessary, the light emitting device can be manufactured at a lower cost.

Examples of the material constituting the light guide plate include materials having excellent light transmittance and molding, such as polycarbonate resin, acrylic resin, amorphous polyolefin resin, and polystyrene resin.
In order to produce a light guide plate having a desired concavo-convex portion, it can be produced, for example, by an injection molding method using a mold having a desired concavo-convex pattern. When a prism row is used for the uneven portion, the prism pitch is preferably 30 to 100 μm. This is because if the prism pitch is smaller than 30 μm, the depth of the V-shaped groove between the prisms becomes shallow, the proportion of light emitted perpendicular to the emission surface decreases, and the luminance decreases. On the other hand, if the thickness is larger than 100 μm, the ratio of reflected light decreases and the luminance decreases.

  The apex angle of the prisms of the first prism row 32 is preferably 80 to 120 degrees. This is because the ratio of the light emitted perpendicular to the emission surface can be increased by increasing the reflected light by causing total reflection and confining the light inside the light guide plate.

  Further, the light guide plate may contain a diffusing agent to further emit light uniformly, or may contain a colorant to emit a desired emission color. A diffusing agent or a colored pigment may be uniformly dispersed in the light guide plate, or may be distributed in an inclined manner. Examples of the material for the diffusing agent include acrylic resin, polycarbonate resin, amorphous polyolefin resin, and polymethylene pentene resin. Various pigments and dyes can be used as the colorant. Moreover, fluorescent dyes and fluorescent pigments can also be used.

  Also, a highly reflective metal film such as Al, Ag, Cu or the like can be formed on the bottom surface of the light guide plate by sputtering or vacuum deposition. Thereby, the reflectance of a bottom face can be raised and the light extraction efficiency can further be improved.

In the present invention, the light source can be any light emitter such as a light-emitting element such as a light bulb, a fluorescent lamp, an LED (Light Emitting Diode), an LD (Laser Diode), or an EL (Electroluminescence).
The light-emitting diode used as the light source in this embodiment can be variously used as long as it can efficiently introduce light into the light guide plate. The light emitting diode may be an SMD (surface light emitting type) light emitting diode or a shell type light emitting diode. Moreover, the LED chip itself which is a light emitting element may be sufficient.

  Examples of the material of the light emitting element include various semiconductors such as BN, SiC, ZnSe, GaN, InGaN, InAlGaN, AlGaN, BAlGaN, and BInAlGaN. Similarly, these elements may contain Si, Zn, or the like as an impurity element to serve as a light emission center. As the semiconductor structure, a homostructure having a MIS junction, a PIN junction, a pn junction, or the like, a heterostructure, or a double heterostructure can be preferably exemplified. Various emission wavelengths can be selected depending on the semiconductor layer material and the mixed crystal ratio. Further, the output can be further improved by adopting a single quantum well structure or a multiple quantum well structure in which the semiconductor layer is formed in a thin film in which a quantum effect is generated.

  Two or more light emitting elements can be used, and two or more light emitting elements can be used. When two or more types are used, various emission colors can be obtained by mixing emission colors. White light can be emitted by making the light emitting elements RGB (red, green, blue) or BY (blue, yellow) and emitting all colors.

In addition, as a light emitting element capable of emitting white light in combination with a phosphor, a nitride semiconductor capable of emitting blue light (In _X Al _Y Ga _1-XY N, 0 ≦ X, 0 ≦ Y, X + Y ≦ 1) is used. The used light-emitting element can be preferably used. In this case, it is preferable to use a YAG: Ce phosphor or a perylene derivative as the phosphor. In the case of a light emitting element that emits ultraviolet light, an alkaline earth metal halogen apatite phosphor activated with Eu containing at least Mn and / or Cl can be used.

  When a nitride semiconductor is used, sapphire, spinel, SiC, Si, ZnO, GaAs, GaN, or the like can be suitably used for the semiconductor substrate. In order to form a nitride semiconductor having good crystallinity with high productivity, it is preferable to use a sapphire substrate. A nitride semiconductor can be formed on the sapphire substrate using the HVPE method, the MOCVD method, or the like. On the sapphire substrate, a buffer layer made of GaN, AlN, GaAlN or the like that becomes non-single crystal by low-temperature growth is formed, and a nitride semiconductor having a pn junction is formed thereon.

As an example of a light-emitting element that can efficiently emit light in an ultraviolet region having a pn junction using a nitride semiconductor, SiO ₂ is formed in a stripe shape on the buffer layer substantially perpendicular to the orientation flat surface of the sapphire substrate. GaN is grown on the stripes using EHV (Epitaxial Lateral Over Growth) using the HVPE method. Subsequently, a first contact layer formed of n-type gallium nitride, a first cladding layer formed of n-type aluminum nitride / gallium, a well layer of indium nitride / aluminum / gallium, and aluminum nitride / gallium are formed by MOCVD. Examples include an active layer having a multiple quantum well structure in which a plurality of barrier layers are stacked, and a double heterostructure in which a second contact layer formed of p-type gallium nitride is sequentially stacked.

  Nitride semiconductors exhibit n-type conductivity without being doped with impurities. In the case of forming a desired n-type nitride semiconductor such as improving luminous efficiency, it is preferable to appropriately introduce Si, Ge, Se, Te, C or the like as an n-type dopant. On the other hand, when forming a p-type nitride semiconductor, it is preferable to dope p-type dopants such as Zn, Mg, Be, Ca, Sr, and Ba. Since a nitride semiconductor is difficult to be converted to a p-type simply by doping with a p-type dopant, it is preferable to reduce the resistance by heating in a furnace or plasma irradiation after the introduction of the p-type dopant. Etching from the p-type side to the surface of the first contact layer exposes each contact layer. A light emitting element made of a nitride semiconductor can be manufactured by forming an electrode on each contact layer and then cutting the semiconductor wafer into chips.

  The planar light emitting device of the present invention can emit light from a light emitting element as it is, and can also emit light from a light emitting element into various colors by a color conversion member. The color conversion member can take various forms, for example, a coating film containing a phosphor may be formed on the incident surface of the light guide plate, and the sheet holding the phosphor may be placed on the exit surface of the light guide plate. It can also be arranged. As a specific color conversion member, it is formed by applying a resin containing a phosphor to a sheet-like base film having a light transmittance of 70% or more with respect to light from the light emitting element, using a roll coater or the like. be able to. As such a base film, a polycarbonate film and a polyester film having high translucency and heat resistance are preferably exemplified. In order to further improve the light emission uniformity, a base film coated with refractive fine particle resin beads or translucent inorganic fine particles, or further embossed with the above film can be preferably used. Moreover, a more uniform white display can be obtained by adding a white pigment together with the phosphor.

The phosphor described above can be used as the phosphor to be contained in the color conversion member. That is, in the case of the light emitting device using a blue light emitting capable nitride semiconductor _{(In X Al Y Ga 1-} X-Y N, 0 ≦ X, 0 ≦ Y, X + Y ≦ 1), YAG is the phosphor: Ce It is preferable to use a phosphor or a perylene derivative. In the case of a light emitting element that emits ultraviolet light, it is preferable to use an alkaline earth metal halogen apatite phosphor activated with Eu containing at least Mn and / or Cl.

Embodiment 2. FIG.
2A and 2B are schematic views showing the structure of the planar light emitting device B according to the present embodiment, where FIG. 2A is a plan view and FIG. 2B is a perspective view. The planar light emitting device B has the same configuration as that of the first embodiment except that the two light source rows are respectively arranged on the opposite side surfaces.
The planar light emitting device B includes a light-transmitting light guide plate 4 and two light source rows 1 and 1, and the two light source rows 1 and 1 are disposed on opposite side surfaces 4 c and 4 c ′ of the light guide plate, respectively. ing. The light source array 1 is composed of a plurality of LEDs 1a arranged in a straight line. Here, the light guide plate 4 includes an output surface 4a that is an upper surface, a bottom surface 4b that faces the output surface 4a, an incident surface 4c on which light from the LED is incident, and an incident surface 4c that faces the incident surface 4c. 'And a pair of side surfaces 4e and 4f adjacent to and opposite to the incident surface 4c. Further, as in the case of the first embodiment, the surface of the light guide plate 4, that is, any one or more surfaces selected from the exit surface 4a, the bottom surface 4b, the entrance surface 4c, 4c ′ side surfaces 4e and 4f. For example, it is possible to form a concavo-convex portion composed of a prism row shown in FIG.

  In the present embodiment, light from a light source is incident from two opposing side surfaces of a light guide plate to improve luminance. That is, light incident from the two incident surfaces is reflected by the prism rows formed on the opposite incident surfaces, so that transmission of light from the incident surfaces is suppressed, and light extraction efficiency can be improved.

Embodiment 3 FIG.
3A and 3B are schematic views showing the structure of the planar light emitting device C according to the present embodiment, where FIG. 3A is a plan view, FIG. 3B is a side view, and FIG. 3C is a perspective view.
The planar light-emitting device according to the present embodiment is a planar light-emitting device having a light source and a light guide plate that causes light from the light source to be incident from the side surface and to be emitted from the upper surface by reflection. One side surface has a concavo-convex portion, the incident surface of the light guide plate has a plurality of step surfaces continuous with a predetermined step from the upper surface to the bottom surface of the light guide plate, and the step surface on the upper surface side is a continuous bottom surface side. The light source is formed so as to protrude in the direction of the light source with respect to the step surface, and the light source is disposed on each of the step surface on the upper surface side and the step surface on the bottom surface side so as to face each step surface. A planar light emitting device characterized by the following.
Furthermore, it is possible to provide a planar light emitting device in which the light sources are alternately arranged on the step surface on the upper surface side and the step surface on the bottom surface side along the longitudinal direction of the incident surface.
Moreover, it can be set as the planar light-emitting device which the said uneven | corrugated | grooved part is a prism row | line | column which consists of many protrusions which have a continuous triangular cross section.
Further, the uneven portion has a side surface facing a side surface on which light from the light source is incident, a side surface adjacent to a side surface on which light from the light source is incident, a side surface on which light from the light source is incident, and an upper surface of the light guide plate The planar light-emitting devices provided respectively in the above.
Further, the light source is disposed so as to face the incident surface of the light guide plate, and a planar light emitting device in which the uneven portion is provided on the incident surface can be obtained.

Hereinafter, the planar light emitting device according to the present embodiment will be described in more detail. The planar light emitting device C shown in FIG. 3 has the same configuration as that of Embodiment 1 except that two light source arrays are arranged on two step surfaces provided on the side surfaces. The planar light emitting device C includes a light transmissive light guide plate 5 and two light source rows 1 and 2.
The incident surface 5c of the light guide plate 5 has a first step surface 51c and a second step surface 52c that are continuous from the upper surface 5a to the bottom surface 5b with a predetermined step, and the first step surface 51c It is formed so as to protrude in the direction of the light source with respect to the second step surface 52c. The first light source row 1 is disposed so as to face the first step surface 51c, and the second light source row 2 is disposed so as to face the second step surface 52c. Here, the first light source row 1 and the second light source row 2 are each composed of a plurality of light sources 1a and 2a arranged linearly in the longitudinal direction of the incident surface, and the light source 1a and the light source 2a are incident. The first step surface 51c and the second step surface 52c are alternately arranged along the longitudinal direction of the surface.

  The light guide plate 5 includes an output surface 5a that is an upper surface, a bottom surface 5b that faces the output surface 5a, an incident surface 5c on which light from the LED is incident, a side surface 5d that faces the incident surface 5c, and an incident surface. It has a pair of side surfaces 5e and 5f that are adjacent to and face 5c. Further, as in the case of the first embodiment, the entire surface of the light guide plate 5 or the surface of the light guide plate 5, that is, the exit surface 5a, the bottom surface 5b, the entrance surface 5c, the 5c ′ side surfaces 5d, 5e and 5f is selected. For example, it is possible to form a concavo-convex portion formed of a prism array shown in FIG.

  Since this embodiment has two light sources on the side surface and high brightness, an extremely strong emission intensity distribution is generated in the vicinity of the LEDs constituting the light sources. However, the light that has entered the light guide plate from the two light sources is reflected inside the light guide plate, part of the light returns to the incident surface, is reflected by the incident surface, and exits from the output surface. Therefore, luminance unevenness in the vicinity of the LED is eliminated, and luminance uniformity can be improved. In particular, by arranging the LEDs 1a and 2a alternately along the longitudinal direction of the incident surface, the intensity distribution of light emission in the vicinity of the LED is made more uniform, resulting in more effective elimination of luminance unevenness in the vicinity of the LED. can do.

  In addition, since the light source array composed of one or more LEDs is arranged on each of the two step surfaces provided on the side surface, a large number of light sources can be arranged on the incident surface without increasing the size of the light guide plate. A light-emitting device can be provided.

  Further, since the light source of the first light source array has a longer optical path than the light source of the second light source array, the luminance is lower than that of the light source of the second light source array, but the directivity is weakened. The color mixing between them becomes high. On the other hand, since the light source of the second light source array has a short optical path, it is less likely to be reflected and scattered inside the light guide plate, resulting in high brightness. Therefore, according to the light emitting device of the present embodiment, it is possible to achieve both high luminance and color mixing.

  In the present embodiment, the case where there are two step surfaces has been described. However, even if the number of step surfaces is three or more, the same effect as in the present embodiment can be obtained.

  In Embodiments 1 to 3, the prism array having the shape shown in FIG. 1B is used. However, the uneven portion used in the present invention is not limited to the prism array having the shape shown in FIG. . For example, the following modifications are possible.

Modification 1
FIG. 4 is a schematic diagram showing the shape of the concavo-convex part of this modification, and shows an example applied to the planar light emitting device of the first embodiment. The concavo-convex portion of this modification is a prism array, and includes a first prism array 32 formed at a predetermined prism pitch and one or more prisms formed between two adjacent prisms of the first prism array. The second prism row 33 is formed so that the cross-sectional area of the prisms of the second prism row 33 is smaller than the cross-sectional area of the prisms of the first prism row 32.
By forming two types of prism rows composed of prisms having different cross-sectional areas, it is possible to increase the proportion of light that is emitted perpendicular to the exit surface by increasing the reflected light.

  FIG. 7 is a schematic enlarged view of the uneven portion of this modification. As described above, the prism pitch of the first prism row is preferably 30 to 100 μm, and the apex angle of the prisms of the first prism row 32 is preferably 80 to 120 degrees. The prism pitch of the second prism row 33 is preferably 5 to 20 μm and the width in the pitch direction is preferably 15 to 60 μm. The apex angle of the prism is preferably 80 to 120 degrees. This is because the ratio of the light emitted perpendicular to the emission surface can be increased by increasing the reflected light by causing total reflection and confining the light inside the light guide plate.

Modification 2
FIG. 5 is a schematic diagram showing the shape of the concavo-convex portion of this modification, and shows an example applied to the planar light emitting device of the first embodiment. The uneven portion of this modification is a prism row, and the first ridges 34 having a plurality of second ridges 34a having a continuous triangular cross section on the surface are continuously arranged at a predetermined pitch. Is formed.
By forming a fine first protrusion on the surface of the second protrusion, the reflected light is increased and the light is confined inside the light guide plate, thereby increasing the proportion of light emitted perpendicular to the emission surface. can do.

Modification 3
FIG. 6 is a schematic diagram showing the shape of the concavo-convex portion of this modification, and shows an example applied to the planar light emitting device of the first embodiment. In the uneven portion of this modified example, pyramid-shaped portions 35 are arranged continuously in the vertical and horizontal directions instead of the prism rows having a triangular cross section.
As in the case of using the prism array, the light from the light source is reflected by the pyramid-shaped portion to increase the reflected light, and the proportion of the light emitted perpendicular to the exit surface can be increased.

  Here, as shown in the schematic enlarged view of FIG. 8, the bottom surface of the pyramid-shaped portion 35 has a square shape, and the length of one side is preferably 10 to 100 μm. This is because if the length of one side is smaller than 10 μm, the depth of the V-shaped groove between the pyramid portions becomes shallow, the proportion of light emitted perpendicular to the emission surface decreases, and the luminance decreases. On the other hand, if the thickness is larger than 100 μm, the ratio of reflected light decreases and the luminance decreases. The angle at which the inclined surfaces facing each other of the prism 35 intersect is preferably 80 to 120 degrees. This is because it is possible to increase the ratio of the light emitted perpendicular to the emission surface by increasing the reflected light. Note that the pyramid portion 35 may be convex in the inner direction of the light guide plate 3 or may be convex in the outer direction of the light guide plate 3.

Examples according to the present invention will be described in detail below. Needless to say, the present invention is not limited to the following examples.
Example 1
1A and 1B are schematic views showing the structure of a planar light emitting device A according to the present embodiment, where FIG. 1A is a plan view and FIG. 1B is a perspective view. The planar light emitting device A includes a translucent light guide plate 3 formed by injection molding using an acrylic resin as a material, and a plurality of surface mounted light emitting devices (SMD) 1a that allow light to enter from a side surface 3c of the light guide plate. And a light source array 1. The light guide plate 3 includes an exit surface 3a, a bottom surface 3b that faces the exit surface 3a, an entrance surface 3c, a side surface 3d that faces the entrance surface 3c, and a pair of side surfaces 3e that are adjacent to and face the entrance surface 3c. 3f. Here, with respect to the incident surface 3c (including the mounting surface 3g facing the light emitting surface of the SMD), the side surface 3d facing the incident surface 3c, and the pair of side surfaces 3e and 3f adjacent to and facing the incident surface 3c, A prism row 31 having an apex angle of 90 degrees and a prism pitch of 60 μm is formed. The SMD in the present embodiment is formed using an LED chip, and is disposed so that the light emitting surface of the SMD faces the incident surface 3 c of the light guide plate 3.
In the planar light emitting device A configured as described above, light incident on the light guide plate from the SMD is reflected in the direction of the inside of the light guide plate by the concavo-convex portion, so that leakage of light from the light guide plate can be prevented. The efficiency of extracting light from the exit surface can be improved without using.

(Example 2)
2A and 2B are schematic views showing the structure of the planar light emitting device B according to this example, where FIG. 2A is a plan view and FIG. 2B is a perspective view. The planar light emitting device B includes a light guide plate 4 formed in the same manner as in the first embodiment, and two light source rows 1 and 1, and the two light source rows 1 and 1 are respectively side surfaces 4 c facing the light guide plate. And 4c '. The light source array 1 is composed of a plurality of SMDs arranged linearly. Here, on the entire surface of the light guide plate 4, that is, on the exit surface 4a, the bottom surface 4b, the entrance surfaces 4c and 4c ′ (including the mounting surface 4g facing the light emitting surface of the SMD), the side surfaces 4e and 4f are the same as in the first embodiment. The concavo-convex portion composed of the prism rows is formed.
In the planar light emitting device B formed as described above, the light incident from the two incident surfaces is reflected by the prism rows formed on the opposing incident surfaces, so that transmission of light from the incident surfaces is suppressed. The light extraction efficiency can be improved.

(Example 3)
3A and 3B are schematic views showing the structure of the planar light emitting device C according to this example, in which FIG. 3A is a plan view, FIG. 3B is a side view, and FIG. 3C is a perspective view.
In the present embodiment, the light guide plate 5 is formed in the same manner as in the first embodiment with the shape shown in FIG. 3, that is, the first step surface 51c continuous from the upper surface 5a to the bottom surface 5b with a predetermined step, and the second step. The first step surface 51c is molded so as to protrude in the direction of the light emitting surface of the SMD with respect to the second step surface 52c. Further, the planar light emitting device C in the present embodiment is formed using SMD as a light source as in the other embodiments. The first light source row 1 is disposed so as to face the first step surface 51c, and the second light source row 2 is disposed so as to face the second step surface 52c. Here, the first light source array 1 and the second light source array 2 are each composed of a plurality of SMDs 1a and SMD2a arranged linearly in the longitudinal direction of the incident surface, and the SMD 1a and SMD 2a are in the longitudinal direction of the incident surface. Are arranged alternately on the first step surface 51c and the second step surface 52c. Here, uneven portions made of prism rows similar to those of the first embodiment are formed on the bottom surface 5b of the light guide plate 5, the incident surface 5c (including the mounting surfaces 5g and 5g 'facing the light emitting surface of the SMD), and the side surfaces 5e and 5f. . According to the planar light emitting device of this example, it is possible to achieve both high luminance and color mixing.

It is a schematic diagram which shows the structure of the planar light-emitting device concerning Embodiment 1 of this invention, (a) is a top view, (b) is a perspective view including a partially expanded view. It is a schematic diagram which shows the structure of the planar light-emitting device concerning Embodiment 2 of this invention, (a) is a top view, (b) is a perspective view. It is a schematic diagram which shows the structure of the planar light-emitting device concerning Embodiment 3 of this invention, (a) is a top view, (b) is a side view, (c) is a perspective view. It is a schematic diagram which shows the structure of the planar light-emitting device which concerns on the modification 1 of this invention, and is a perspective view including a partially expanded view. It is a schematic diagram which shows the structure of the planar light-emitting device which concerns on the modification 2 of this invention, and is a perspective view including a partially expanded view. It is a schematic diagram which shows the structure of the planar light-emitting device which concerns on the modification 3 of this invention, and is a perspective view including a partially expanded view. It is a model enlarged view which shows the surface shape of the planar light-emitting device which concerns on the modification 1 of this invention. It is a model enlarged view which shows the surface shape of the planar light-emitting device concerning the modification 3 of this invention. It is a schematic cross section which shows the structure of the conventional planar light-emitting device.

Explanation of symbols

1, 2 Light source array, 1a, 2a Light source, 3, 4, 5 Light guide plate, 3a, 4a, 5a Upper surface (emission surface), 3b, 4b, 5b Bottom surface, 3c, 4c, 4c ', 5c Side surface (incident surface) 3d, 4d, 5d side surface, 3e, 4e, 5e side surface, 3f, 4f, 5f side surface, 3g, 4g, 5g, 5g 'mounting surface, 31 prism, 32 first prism row, 33 second prism row, 34 th 1 protrusion, 34a 2nd protrusion, 35 pyramid shape part, 51c 1st step surface, 52c 2nd step surface, A, B, C planar light-emitting device.

Claims (8)

A light-emitting device having a light source and a light guide plate that allows light from the light source to be incident from a side surface and emitted from the upper surface by reflection,
An uneven portion is provided on at least one side surface of the light guide plate, and the uneven portion is a prism row composed of a plurality of protrusions having a continuous triangular step surface,
The prism row includes a first prism row formed at a predetermined prism pitch, and a second prism row formed between two adjacent prisms of the first prism row,
The planar light-emitting device, wherein a cross-sectional area of the prisms of the second prism row is smaller than a cross-sectional area of the prisms of the first prism row. A light-emitting device having a light source and a light guide plate that allows light from the light source to be incident from a side surface and emitted from the upper surface by reflection,
An uneven portion is provided on at least one side surface of the light guide plate, and the uneven portion is a prism row composed of a plurality of protrusions having a continuous triangular step surface,
The ridge is composed of a first ridge formed continuously at a predetermined pitch and a plurality of second ridges formed continuously on the surface of the first protrusion. A planar light emitting device. The planar light-emitting device according to claim 1, wherein the uneven portion is provided on a side surface facing a side surface on which light from the light source is incident. The planar light-emitting device according to claim 1, wherein the uneven portion is provided on a side surface adjacent to a side surface on which light from the light source is incident. The planar light-emitting device according to claim 1, wherein the uneven portion is provided on a side surface on which light from the light source is incident. The planar light-emitting device according to claim 1, wherein the uneven portion is provided on an upper surface of the light guide plate. The planar light-emitting device according to claim 1, wherein the light source is disposed so as to face an incident surface of the light guide plate, and the uneven portion is provided on the incident surface. The planar light emitting device according to any one of claims 1 to 7, wherein a pair of side surfaces of the light guide plate facing each other is used as an incident surface, and the light source is disposed opposite to each of the pair of incident surfaces.

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